Here in Mississippi, we are on the verge of getting yet another round of wintry weather. We missed the worst parts of the Groundhog Day Blizzard and even the severe weather was, for the most part, a whimper rather than a roar. However, our luck is about to run out. A system from the Gulf of Mexico is entering the area, and after vacillating for days, the forecasters (both human and computer) have reached a certain amount of consensus about what type of precipitation it will produce and for where.
The writing was actually on the wall last night, in my opinion, when both the 00Z NAM and the 00Z GFS came in with very similar QPF forecasts, both in amount, in type, and in geographic location. What they predicted was not good: up to 3/4 inch of freezing rain, based on the soundings, plus snow, sleet, and rain mixed in (what they call a “wintry mix”). I am not completely sold on 3/4 of an inch of freezing rain now, because it is a bit colder today than expected. This observation ties in with my general philosophy for using the computer models. I don’t pay that much attention to what the big flagship models say for short-term forecasts less than a day out, because they do not accommodate actual observations in their forecasts. Models exist that do, and if you are going to use any models for “nowcasting,” these should be the ones rather than models like the GFS and NAM. So whatever those two are saying today, I’m not paying attention to it. Instead, I am looking at what is happening, and what is happening is that there is more precipitation showing up on radar than the models “believed,” and the temperatures are colder. Not noticeably colder, mind, but just cold enough that it could, I hope, mitigate the amount of freezing rain by changing over to sleet and snow instead.
I think that areas north of I-20 are all going to get something that is frozen. Unlike the last snow event that we had in the South, the one of January 9-11, I do not expect that north Mississippi—the areas that are in the Memphis National Weather Service office’s region—will hit the jackpot. Instead, all indications are that QPF and therefore accumulated precipitation will drop off sharply north of Highway 82 (perhaps Highway 78). The belt of maximum precipitation with this system should be a bit farther south than the January storm.
There will be freezing rain for pretty much every area that gets anything frozen. Fortunately, I don’t think it’s going to be as bad as it looked last night, and it should be mixed in with sleet and snow. The atmosphere is hovering around freezing at several levels, and this will continue until it warms up Friday morning and the precipitation shifts to plain rain. The rain may help to melt whatever falls tonight and early Friday morning. Most of what happens on Friday will be a tapering off, especially since the observed QPF with this system is coming in stronger and a bit earlier than the computers predicted.
There is actually the possibility of yet another round of something in the middle of next week, after a brief “warm” spell this weekend (don’t hold your breath waiting for springlike conditions like what we had last weekend, however; the warmest high will be about 52 on Sunday). It’s too early to say just what this will be, especially since the safe thing to do with respect to such forecasts in the South is to be conservative and forecast cold rain at first, and then modify the forecast as the event approaches—if conditions warrant. Right now, a high of 38F on Wednesday does not warrant modifying the long-term forecast, as utterly miserable as rain would be in that. We’ll have to wait a bit longer to see how next week’s system shakes out, so let’s take this one winter storm at a time for now.
